//    OpenVPN -- An application to securely tunnel IP networks
//               over a single port, with support for SSL/TLS-based
//               session authentication and key exchange,
//               packet encryption, packet authentication, and
//               packet compression.
//
//    Copyright (C) 2012-2022 OpenVPN Inc.
//
//    This program is free software: you can redistribute it and/or modify
//    it under the terms of the GNU Affero General Public License Version 3
//    as published by the Free Software Foundation.
//
//    This program is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//    GNU Affero General Public License for more details.
//
//    You should have received a copy of the GNU Affero General Public License
//    along with this program in the COPYING file.
//    If not, see <http://www.gnu.org/licenses/>.

#ifndef OPENVPN_LOG_LOGPERIOD_H
#define OPENVPN_LOG_LOGPERIOD_H

#include <sys/time.h> // for time_t

#include <string>
#include <sstream>
#include <iomanip> // for setfill and setw

#include <openvpn/common/olong.hpp>
#include <openvpn/common/exception.hpp>
#include <openvpn/time/time.hpp>
#include <openvpn/time/timestr.hpp>

namespace openvpn {
class LogPeriod
{
  public:
    OPENVPN_EXCEPTION(log_period_error);

    enum Period
    {
        UNDEF,
        DAILY,
        HOURLY,
        BY_MINUTE,
    };

    LogPeriod()
        : start_(0),
          end_(0),
          period_(UNDEF)
    {
    }

    LogPeriod(const Period period, const time_t base)
    {
        period_ = period;
        const olong p = period_sec(period_);
        start_ = period_base(period_, base);
        end_ = start_ + p;
    }

    LogPeriod(const LogPeriod &other, const int index)
    {
        period_ = other.period_;
        const olong p = period_sec(period_);
        start_ = other.start_ + p * olong(index);
        end_ = start_ + p;
    }

    bool is_current(const time_t now) const
    {
        const olong onow = olong(now);
        return onow >= start_ && onow < end_;
    }

    bool defined() const
    {
        return period_ != UNDEF;
    }

    time_t expires_in(const time_t now)
    {
        const olong onow = olong(now);
        if (onow < end_)
            return end_ - onow;
        else
            return 0;
    }

    std::string to_string_verbose() const
    {
        return date_time(start_) + " -> " + date_time(end_);
    }

    std::string to_string() const
    {
        std::ostringstream os;
        struct tm lt;
        const time_t time = time_t(start_);
        if (!localtime_r(&time, &lt))
            throw log_period_error("to_string localtime_r");
        os << std::setfill('0');
        os << std::setw(4) << (lt.tm_year + 1900) << '.' << std::setw(2) << (lt.tm_mon + 1) << '.' << std::setw(2) << lt.tm_mday;
        if (period_ == HOURLY || period_ == BY_MINUTE)
            os << '-' << std::setw(2) << lt.tm_hour << ':' << std::setw(2) << lt.tm_min;
        return os.str();
    }

    static Period period_from_string(const std::string &str)
    {
        if (str == "daily")
            return DAILY;
        else if (str == "hourly")
            return HOURLY;
        else if (str == "by_minute")
            return BY_MINUTE;
        else
            throw log_period_error("unknown period: " + str);
    }

  private:
    static olong period_sec(const Period p)
    {
        switch (p)
        {
        case DAILY:
            return 86400;
        case HOURLY:
            return 3600;
        case BY_MINUTE:
            return 60;
        default:
            throw log_period_error("undefined period");
        }
    }

    static olong period_base(const Period p, const time_t time)
    {
        struct tm lt;
        if (!localtime_r(&time, &lt))
            throw log_period_error("period_base localtime_r");
        switch (p)
        {
        case DAILY:
            lt.tm_hour = 0;
            lt.tm_min = 0;
            lt.tm_sec = 0;
            break;
        case HOURLY:
            lt.tm_min = 0;
            lt.tm_sec = 0;
            break;
        case BY_MINUTE:
            lt.tm_sec = 0;
            break;
        default:
            throw log_period_error("unknown period");
        }
        const time_t ret = mktime(&lt);
        if (ret == -1)
            throw log_period_error("mktime");
        return olong(ret);
    }

  private:
    olong start_;
    olong end_;
    Period period_;
};
} // namespace openvpn

#endif
